Rod Knock Flathead 226

Bartman1959

Bartman1959

I have a rod knock in my 48 F1 226. From everything I've read, rod bearings are the cause 99% of the time, and can be replaced while the engine is still in the truck without much problem.
So here are my questions:
1) How do I know what size bearings to order as a direct replacement without the crank being machined?
2) Do I only replace the bearing that has the knock, or replace all of them?
3) Has anyone done this job, and if so, what all was involved?
 
Bartman1959":1n48orzj said:
I have a rod knock in my 48 F1 226. From everything I've read, rod bearings are the cause 99% of the time, and can be replaced while the engine is still in the truck without much problem.
So here are my questions:
1) How do I know what size bearings to order as a direct replacement without the crank being machined?
2) Do I only replace the bearing that has the knock, or replace all of them?
3) Has anyone done this job, and if so, what all was involved?
Click to expand...

i have done similar jobs in the past. the nice thin about the inline six is that it is fairly easy to replace the bearing with the engine in the car.

1) what you want to do is look at the back of the bearing insert. it will tell you what the part number of the bearing is, who the manufacturer is, and what undersize if any. if the bearing is undersized, you will see something like "US .010". that tells you the bearing is .010" undersized, and when ordering bearings you would tell the parts counterman you need that undersize bearing. better to take the old bearing in so the counterman can see it in person.

2) unless there is a problem with the one bearing, i say replace them all. at the very least check them to see if they are out of spec clearance wise. a little plastigage really helps here.

3) after dropping the oil pan, you need to start by putting the first rod at bottom dead center. this will give you plenty of room to remove the bearing and insert the new one. the hardest part is making sure the bearing in the rod is properly seated before you reassemble the rod cap. the bearing insert in the rod cap is easy since you have complete access to it. remember to coat the bearings with some assembly lube before you install the caps and torque them down.

one more thing, if you do this in the car, make sure you eliminate as much dust and debris as possible from your work area. you dont want that stuff in your freshened up motor.
 
it is a fairly straight forward and easy job, just pay attention to the details. and remember to use a good assembly lube when you put the rods and mains back together.
 
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